Transitioning from the use of gasoline vehicles to electric vehicles is important in the effort to solve the global environmental problem. Energy storage devices such as non-aqueous electrolyte secondary batteries are one option for powering such electric vehicles.
In conventional energy storage devices, the container of the energy storage device includes a through hole. During production, an electrolyte is injected into the container through this through hole and contained in the container by sealing the through hole with a sealing member (for example, see Patent Literature (PTL) 1: Japanese Unexamined Patent Application Publication No. 2009-199819). In this energy storage device, the sealing member is fixed to the container while it plugs the through hole by welding the outer edge of the sealing member to the container.